I have a dashboard with an input form that triggers a workflow to update some device tag values.
I had payload tag labelled incorrectly, so when I tried to update that tag without a corresponding payload value, it actually deleted the device tag completely.
If a tag is updated without a value (i.e. updating a tag without a corresponding payload value), the tag will be removed, as you have seen. Just as we do not allow you to save a device tag in the platform without a value:
@Lars_Andersson I have this same issue, it actually caused me quite a headache, the next time the workflow runs I am trying to read tags which no longer exist and the workflow fails.
I have protected the system by adding stricter payload validation, hopefully removing the possibility that a tag value can ever be accidentally deleted, however it would be good to have a persistent tag, or perhaps the option for it.